Nag Republican wearing tights (5)
I believe the answer is:
horse
'nag' is the definition.
(I've seen this before)
'republican wearing tights' is the wordplay.
'republican' becomes 'r' (abbreviation).
'wearing' indicates putting letters inside.
'tights' becomes 'hose' ('hose' can be a synonym of 'tights').
'r' going within 'hose' is 'HORSE'.
(Other definitions for horse that I've seen before include "Eg, mare" , "farm animal" , "Shore (anag)" , "Stallion, e.g." , "Equid" .)