Number of pills required by queasy sea dog (6)
I believe the answer is:
dosage
'number of pills required' is the definition.
'queasy sea dog' is the wordplay.
'queasy' indicates anagramming the letters.
'sea'+'dog'='seadog'
'seadog' anagrammed gives 'DOSAGE'.
'by' acts as a link.
(Other definitions for dosage that I've seen before include "Giving of medicine in prescribed amount" , "Prescribed amount of drug" , "Provision of medicine in prescribed amounts" , "Sea dog (anag)" , "amount of 14 [WONDER DRUG], say" .)