Left in chamber to produce young whales (5)
I believe the answer is:
calve
'produce young whales' is the definition.
'left in chamber' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'chamber' becomes 'cave' (I have seen 'Underground chamber' mean 'cave' so perhaps 'chamber' could also mean 'cave').
'l' placed into 'cave' is 'CALVE'.
'to' acts as a link.
(Other definitions for calve that I've seen before include "Give birth to (an iceberg?)" , "Bear on farm" , "create seal" , "Give birth to young cow" , "bear on ranch" .)