Lively sex embraced by excited spider (8)
I believe the answer is:
spirited
'lively' is the definition.
(associated in meaning)
'sex embraced by excited spider' is the wordplay.
'sex' becomes 'it' (a common euphemism).
'embraced by' means one lot of letters goes inside another.
'excited' indicates an anagram.
'spider' is an anagram of 'spired'.
'it' put within 'spired' is 'SPIRITED'.
(Other definitions for spirited that I've seen before include "Riptides of lively kind" , "In game" , "Vivacious" , "with brio" , "Mettlesome" .)