Go through fast again? That's suggestive (8)
I believe the answer is:
redolent
'suggestive' is the definition.
(thesaurus)
'go through fast again?' is the wordplay.
'go' becomes 'do' (doing is a kind of going).
'through' means one lot of letters goes inside another (I've seen this in other clues).
'fast again?' becomes 'relent' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'do' placed into 'relent' is 'REDOLENT'.
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for redolent that I've seen before include "Aromatic" , "Smelling of, evocative" , "Strongly reminiscent (of something)" , "Smelling strongly or suggestive of it" , "Do relent, being full of memories or smells" .)