Leggy bird, one proceeding with difficulty? (5)
I believe the answer is:
wader
'leggy bird' is the definition.
'wader' can be an answer for 'bird' (wader is a kind of bird). I'm not sure about the 'leggy' bit.
I cannot understand how the remainder of the clue works.
(Other definitions for wader that I've seen before include "Heron, say" , "Long-legged shore bird" , "Snipe maybe" , "Long waterproof boot" , "crane, perhaps" .)