Hanging Gardens ultimately seen in Cornish town (5)
I believe the answer is:
loose
'hanging' is the definition.
(thesaurus)
'gardens ultimately seen in cornish town' is the wordplay.
'ultimately' says to take the final letters.
'seen in' means one lot of letters goes inside another.
'cornish town' becomes 'looe' (I've seen this before).
The final letter of 'gardens' is 's'.
's' placed within 'looe' is 'LOOSE'.
(Other definitions for loose that I've seen before include "escaped!" , "Not tightly fixed" , "Free or immoral" , "Slack; not exact" , "Not bound" .)