Iron both ways, beginning with crease and ribbon round top of vest, working well (9)
I believe the answer is:
effective
'round top of vest working well' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I don't see?
'iron both ways beginning with crease and ribbon' is the wordplay.
I cannot really see how this works, but
'iron' could be 'fe' (chemical symbol for iron) and 'fe' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for effective that I've seen before include "Practical or operative" , "Powerful" , "Striking" , "Practical and productive" , "Competent - impressive" .)