White breaks second-rate centre of Grand Master (5)
I believe the answer is:
bwana
'master' is the definition.
(I've seen this before)
'white breaks second-rate centre of grand' is the wordplay.
'white' becomes 'wan' (very pale).
'breaks' is an insertion indicator.
'second rate' becomes 'b'.
'centre of' says to take the centre.
The middle of 'grand' is 'a'.
'b'+'a'='ba'
'wan' placed inside 'ba' is 'BWANA'.
(Other definitions for bwana that I've seen before include "respected white man once?" , "master in Africa" , "Old master" , "African boss" , "Master's" .)