Something played live in playing field (5)
I believe the answer is:
rebec
'something played' is the definition.
(stringed instrument)
'live in playing field' is the wordplay.
'live' becomes 'be' (synonyms).
'in' indicates putting letters inside.
'playing field' becomes 'rec' (short for recreation ground).
'be' placed into 'rec' is 'REBEC'.
(Other definitions for rebec that I've seen before include "Old stringed instrument" , "Mediaeval stringed instrument" , "Medieval bowed instrument" .)