Composer from Southend composed lots (5)
I believe the answer is:
holst
'composer' is the definition.
(Gustav Holst)
'southend composed lots' is the wordplay.
I cannot really understand how this works, but
an anagram of 'lots' is 'olst' which is present in the answer.
A single letter 'h' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'from' is the link.
Can you help me to learn more?
(Other definitions for holst that I've seen before include "Scorer" , "Gustav - (The Planets)" , "Gustav --, English composer" , "He scored" , "British composer, 1874-1934" .)