Medal a Yankee wears, perhaps (5)
I believe the answer is:
maybe
'perhaps' is the definition.
(I know that perhaps can be written as maybe)
'medal a yankee wears' is the wordplay.
'medal' becomes 'mbe' (Member of the British Empire medal).
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'wears' means one lot of letters goes inside another.
'a'+'y'='ay'
'mbe' going around 'ay' is 'MAYBE'.
(Other definitions for maybe that I've seen before include "Perhaps, possibly" , "Perhaps, might happen" .)