Shell to retrieve found in swimmer's lung? (8)
I believe the answer is:
breather
'shell to retrieve found in swimmer's lung?' is the definition.
I can't tell whether this defines the answer.
'shell to retrieve found in swimmer's lung?' is the wordplay.
'shell' means to remove the middle letters (I've seen 'shell of' mean this).
'to retrieve' becomes 'rescue' (I've seen this before).
'found in' is an insertion indicator.
'swimmer's lung?' becomes 'bather' (I can't explain this - if you can you should give a lot more credence to this answer).
'rescue' with its middle removed is 're'.
're' placed into 'bather' is 'BREATHER'.
Can you help me to learn more?
(Other definitions for breather that I've seen before include "lung, possibly?" , "Short pause for rest" , "Short respite" , "Brief pause for rest" , "time off work" .)