Daughter occupying position on first of ensembles composed (6)
I believe the answer is:
sedate
'composed' is the definition.
(thesaurus)
'daughter occupying position on first of ensembles' is the wordplay.
'daughter' becomes 'd'.
'occupying' means one lot of letters goes inside another.
'position' becomes 'seat' (seating is a kind of positioning**).
'on' means one lot of letters go next to another.
'first of' says to take the initial letters.
The initial letter of 'ensembles' is 'e'.
'd' inserted inside 'seat' is 'sedat'.
'sedat'+'e'='SEDATE'
(Other definitions for sedate that I've seen before include "Teased into being calm" , "Unhurried; drug" , "Calm, unhurried" , "Dignified - staid" , "Tranquilise" .)