Time to compose a poem with perfect ending (5)
I believe the answer is:
tempo
'time' is the definition.
(tempo is a kind of time)
'compose a poem with perfect ending' is the wordplay.
'compose' is an anagram indicator.
'with' says to put letters next to each other.
'ending' says to take the final letters.
The final letter of 'perfect' is 't'.
'poem' anagrammed gives 'empo'.
'empo' put after 't' is 'TEMPO'.
'to' acts as a link.
(Other definitions for tempo that I've seen before include "Time (music)" , "Speed of 3A" , "(Musically) the speed to be played" , "Pace of a musical piece" , "Rate and rhythm in music" .)