Dummy run follows company beginning to muster strength (9)
I believe the answer is:
comforter
'dummy' is the definition.
(I've seen this before)
'run follows company beginning to muster strength' is the wordplay.
'run' becomes 'r' (cricket abbreviation).
'follows' means one lot of letters go next to another.
'company' becomes 'co' (abbreviation).
'beginning to' indicates taking the first letters.
'strength' becomes 'forte' (synonyms).
The initial letter of 'muster' is 'm'.
'co'+'m'+'forte'='comforte'
'r' after 'comforte' is 'COMFORTER'.
(Other definitions for comforter that I've seen before include "one that brings relief" , "Baby's dummy" , "Job didn't need such as this" .)