Master coach on reflection, worried about pitcher (9)
I believe the answer is:
subjugate
'master' is the definition.
(subjugating is a kind of mastering)
'coach on reflection worried about pitcher' is the wordplay.
'coach' becomes 'bus' (synonyms).
'on reflection' is a reversal indicator.
'worried' becomes 'ate' (something worrying may eat someone up).
'about' means one lot of letters go next to another.
'pitcher' becomes 'jug' (I've seen this before).
'bus' back-to-front is 'sub'.
'ate' after 'jug' is 'jugate'.
'sub'+'jugate'='SUBJUGATE'
(Other definitions for subjugate that I've seen before include "Crush" , "Master" , "Bring under one's sway" , "cow" , "Bring under domination" .)