Using harp in the southeast, composed short musical passage (6)
I believe the answer is:
phrase
'short musical passage' is the definition.
(I've seen this in another clue)
'using harp in the southeast composed' is the wordplay.
I cannot quite see how this works, but
an anagram of 'harp' is 'phra' which is within the answer.
'southeast' could be 'se' (synonyms) and 'se' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for phrase that I've seen before include "Saying" , "Sentence unit" , "Group of words as unit" , "Short musical passage" , "Group of words forming part of a sentence" .)