Bit of a thin time, let's suggest (4)
I believe the answer is:
hint
'suggest' is the definition.
(synonyms)
'bit of a thin time let's' is the wordplay.
'bit of' indicates the answer is hidden within the clue.
'HINT' is hidden within 'thin time lets'.
(Other definitions for hint that I've seen before include "Piece of advice" , "Intimate" , "Tip - small amount" , "CRT screen coating" , "Taste" .)