Fast runner, though no winger: what about joining the Gunners? (4)
I believe the answer is:
rhea
'fast runner' is the definition.
(I've seen this before)
'about joining the gunners?' is the wordplay.
'about' means one lot of letters goes inside another.
'joining' becomes 'he' (I can't justify this - if you can you should believe this answer much more).
'the gunners?' becomes 'ra' (Royal Artillery).
'he' going within 'ra' is 'RHEA'.
'though no winger what' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for rhea that I've seen before include "Moon" , "nonflyer" , "S American runner" , "Flightless bird -- satellite of Saturn" , "Fertility goddess in ancient Greek mythology" .)