Potential seed put you, say, in love madly (5)
I believe the answer is:
ovule
'potential seed' is the definition.
(I've seen this in another clue)
'you say in love madly' is the wordplay.
'you say' becomes 'u' ('you' as it sounds).
'in' means one lot of letters goes inside another.
'madly' is an anagram indicator.
'love' is an anagram of 'ovle'.
'u' placed into 'ovle' is 'OVULE'.
'put' acts as a link.
(Other definitions for ovule that I've seen before include "Undeveloped seed" , "Egg-cell in a plant" , "Egg cell" , "Small plant structure that develops into a seed" , "Small body containing the female germ cell of a plant" .)