Tried fitting horse's heart in cooker (6)
I believe the answer is:
strove
'tried' is the definition.
(I've seen this before)
'fitting horse's heart in cooker' is the wordplay.
'fitting horse's heart' becomes 'r' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'cooker' becomes 'stove' (I've seen this before).
'r' placed within 'stove' is 'STROVE'.
Can you help me to learn more?
(Other definitions for strove that I've seen before include "Voters (anag) - made every effort" , "Made great efforts" , "Endeavoured" , "Struggled" , "Tried hard for voters" .)