Drawers maybe start to scribble a couple of lines in writing (6)
I believe the answer is:
smalls
'drawers maybe' is the definition.
(drawers are an example of underwear ie smalls)
'start to scribble a couple of lines in writing' is the wordplay.
'a couple of lines' can mean two replacements for 'line'.
'start to' suggests taking the first letters.
'line' becomes 'l'.
'line' becomes 'l'.
'in' is an insertion indicator.
'writing' becomes 'mas' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The first letter of 'scribble' is 's'.
'l'+'l'='ll'
'll' placed within 'mas' is 'malls'.
's'+'malls'='SMALLS'
(Other definitions for smalls that I've seen before include "bloomers" , "Slips perhaps" , "Undersized underwear?" , "Underwear (colloq.)" , "Items of a personal nature" .)