Fun for fliers (5)
I believe the answer is:
larks
'fliers' is the definition.
(lark is a kind of bird)
'fun for' is the wordplay.
'fun' becomes 'lark' (I've seen this before).
'for' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'lark'+'s'='LARKS'
Can you help me to learn more?
(Other definitions for larks that I've seen before include "Small songbirds" , "Early birds" , "guys" , "High jinks" , "Birds; fun" .)