Second tenor given central part of sketch in short piece of music (5)
I believe the answer is:
motet
'short piece of music' is the definition.
'second tenor given central part of sketch' is the subsidiary indication.
'second' becomes 'mo' (both are short periods of time).
'tenor' becomes 't'.
'given' means one lot of letters go next to another.
'central part of' indicates the central letters.
The centre of 'sketch' is 'et'.
'mo'+'t'+'et'='motet'
'in' is the link.
(Other definitions for motet that I've seen before include "Musical composition" , "Piece for choir" , "Word; fixed period" , "Creating sacred piece" , "Short sacred vocal work" .)