Excessive love admitted by crazy meter maid (10)
I believe the answer is:
immoderate
'excessive' is the definition.
('immoderate' can be similar in meaning to 'excessive')
'love admitted by crazy meter maid' is the wordplay.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'admitted by' means one lot of letters goes inside another.
'crazy' is an anagram indicator.
'meter'+'maid'='metermaid'
'metermaid' is an anagram of 'immderate'.
'o' placed inside 'immderate' is 'IMMODERATE'.
(Other definitions for immoderate that I've seen before include "Reckless" , "Extravagant" , "Excessive" , "over the top" .)