Thin sort of suggestion (4)
I believe the answer is:
hint
'suggestion' is the definition.
(I know that suggestion can be written as hint)
'thin sort' is the wordplay.
'sort' is an anagram indicator.
'thin' is an anagram of 'HINT'.
'of' acts as a link.
(Other definitions for hint that I've seen before include "Indicate indirectly" , "signal" , "Thin sort of slight indication" , "suspicion" , "Tip-off" .)