Criminal nervous about unknown journalist turning up for meeting (10)
I believe the answer is:
rendezvous
'criminal nervous' is the definition.
I can't judge whether this defines the answer.
'about unknown journalist turning up for meeting' is the wordplay.
'about' means one lot of letters goes inside another.
'unknown' becomes 'z' (algebra).
'journalist' becomes 'ed' (short for editor).
'turning up' is a reversal indicator.
'for meeting' becomes 'renvous' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'z'+'ed'='zed'
'zed' back-to-front is 'dez'.
'dez' inserted into 'renvous' is 'RENDEZVOUS'.
Can you help me to learn more?
(Other definitions for rendezvous that I've seen before include "Arranged meeting" , "Meet - meeting" , "Meeting place" , "Date" , "Meeting-place" .)