What's left of uniform kept in lodge (7)
I believe the answer is:
residue
'what's left' is the definition.
(I've seen this before)
'uniform kept in lodge' is the wordplay.
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'kept in' means one lot of letters goes inside another.
'lodge' becomes 'reside' (I've seen this before**).
'u' inserted inside 'reside' is 'RESIDUE'.
'of' is the link.
(Other definitions for residue that I've seen before include "Leftovers" , "grounds" , "Matter left behind after other parts have been taken away" , "Stuff left over" , "Remainder, leftover" .)