Coach Spanish lady to project in part that matters (8,3)
I believe the answer is:
business end
'part that matters' is the definition.
(I've seen this in another clue)
'coach spanish lady to project' is the wordplay.
'coach' becomes 'bus' (synonyms).
'spanish lady' becomes 'ines' (Ines is a common Spanish name).
'to project' becomes 'send' (I've seen this in another clue).
'bus'+'ines'+'send'='BUSINESS END'
'in' is the link.
(Other definitions for business end that I've seen before include "That's the bit that works" , "part doing the work" , "Liquidation" , "Device's functional part" .)