With garden gone to seed, he's saved pineapple (4,7)
I believe the answer is:
hand grenade
'pineapple' is the definition.
(pineapple can informally mean a grenade)
'with garden gone to seed he's saved' is the wordplay.
I cannot really understand how this works, but
'with' could be 'and' and 'and' is found in the answer.
an anagram of 'garden' is 'grenad' which is located in the answer.
'he' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hand grenade that I've seen before include "Small thrown bomb" , "Explosive device that is thrown" , "pineapple" , "Manually launched explosive device" , "Military explosive" .)