He'll risk a stroll within the confines of Gibraltar (7)
I believe the answer is:
gambler
'he'll risk a' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'stroll within the confines of gibraltar' is the wordplay.
'stroll' becomes 'amble' (synonyms).
'within' means one lot of letters goes inside another.
'the confines of' says to hollow out the word (remove centre letters) (the letters at the borders or confines are used).
'gibraltar' with its middle taken out is 'gr'.
'amble' inserted inside 'gr' is 'GAMBLER'.
Can you help me to learn more?
(Other definitions for gambler that I've seen before include "Better" , "Casino punter" , "I bet?" , "Speculator" , "One who takes risks" .)