nirdhuuyamaanaas tv atha leshato 'pi
tiShTheyur ev' aakushalaa vitarkaaH
sevyo vidhir vismaraNaaya teShaaM
If, though they are being shaken off,
There is any lingering trace of unhelpful thoughts,
One should get on with something else,
such as study or a physical task,
As a means of consigning those thoughts to oblivion.
Formal practice is time when one can devote oneself wholly to shaking off those unhelpful thoughts which are at the root of faulty reactions.
In getting on with something other than formal practice sometimes this very thought of shaking off thoughts is itself naturally shaken off.
Marjory Barlow used to say "Go into movement without a care in the world -- let it come out in the wash."
This verse is an explicit recognition of the importance of banishing unhelpful thoughts.
It is also an implicit recognition of the importance of formal practice, central to which is formal sitting practice -- because without formal practice, there can never be "something else." And without something else, there can never be formal sitting practice.
But if evil thoughts, though shaken off, should subsist even a little, you must labour for their obliteration by some other means such as study, action etc.
However, unwholesome thoughts may persist to a small extent, though they are being shaken loose; they should be obliterated by taking up different methods, such as study and work.
nirdhuuyamaanaaH = nom. pl. pres. passive participle nir-√dhuu: to shake , agitate , shake out or off , scatter , remove , destroy , expel , reject
tu: but, however
atha: (connecting particle)
leshataH: very slightly
lesha: m. a small part or portion , particle , atom , little bit or slight trace of
-taH: (ablative/adverbial suffix)
tiShTheyuH = 3rd person plural, optative of stha: to stand, remain
akushalaaH (nom. pl. m.): inauspicious, evil; not clever, not constructive
vitarkaaH (nom. pl): m. ideas, fancies, thoughts
kaarya: n. work or business to be done , duty , affair
antaraiH = inst. pl. antara: n. (ifc.) , different , other , another
adhyayana: reading , studying , especially the vedas (one of the six duties of a Brahman)
kriyaa: action , undertaking , activity , work , labour; bodily action , exercise of the limbs
aadhyaiH (inst. pl): being at the beginning , first (= aadi, et cetera)
sevyaH (nom. sg. m., from gerunidive of sev): to be resorted to; to be followed (as a path)
vidhiH (nom. sg.): m. method, manner of acting, means, expedient
vismaraNaaya = dative of vismaraNa: n. the act of forgetting , oblivion
teShaam (genitive, plural of saH): of them