Photos including unknown drug in a feature of the nervous system (7)
I believe the answer is:
synapse
'nervous system' is the definition.
(thesaurus)
'photos including unknown drug' is the wordplay.
'photos' becomes 'snaps' (I've seen this before).
'including' is an insertion indicator.
'unknown' becomes 'y' (algebra).
'drug' becomes 'e' (e is another name for ecstasy).
'snaps' placed around 'y' is 'synaps'.
'synaps'+'e'='SYNAPSE'
'in a feature of the' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for synapse that I've seen before include "Part of the nervous system" , "Nerve junction" , "Where two nerve cells meet" , "Nerve cell connector" , "Gap between nerve cells across which signals pass" .)