Trip facilitator's support touring Croatia's capital (4)
I believe the answer is:
acid
'trip facilitator's' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'support touring croatia's capital' is the wordplay.
'support' becomes 'aid' (to aid is to help or support).
'touring' is an insertion indicator (touring can mean going round).
'capital' indicates taking the first letters.
The initial letter of 'croatias' is 'c'.
'aid' enclosing 'c' is 'ACID'.
Can you help me to learn more?
(Other definitions for acid that I've seen before include "Bitter; biting" , "Corrosive fluid" , "Sarcastic (could be sulphuric?)" , "Sour, sharp-tasting" , "Bitter substance" .)