Choose your top, being fussy (5)
I believe the answer is:
picky
'being fussy' is the definition.
(I've seen this in another clue)
'choose your' is the wordplay.
'choose' becomes 'pick' (picking is a kind of choosing).
'your' becomes 'y' (this might be a standard abbreviation I've not previously seen).
'pick'+'y'='PICKY'
'top' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for picky that I've seen before include "Excessively particular" , "Excessively fastidious" , "Choosy" , "Discriminating" , "Finicky" .)