Start to put on pair of smalls and hug (5)
I believe the answer is:
press
'hug' is the definition.
(thesaurus)
'start to put on pair of smalls' is the wordplay.
'start to' suggests taking the first letters.
'on' becomes 're' ('on' can be mean 'with reference to').
'pair of' indicates the doubling of some letters (I've seen 'pair' mean this).
'smalls' becomes 's' (this could be a standard abbreviation of which I'm unaware).
The first letter of 'put' is 'p'.
's' duplicated is 'ss'.
'p'+'re'+'ss'='PRESS'
'and' is the link.
(Other definitions for press that I've seen before include "To iron; a cupboard" , "publicity" , "Enlist crew" , "Newspapers - use button!" , "Urgency" .)