Fear of deer on organised freight (5,6)
I believe the answer is:
stage fright
'fear' is the definition.
(I know that stage fright is a phobia)
'deer on organised freight' is the wordplay.
'deer' becomes 'stag' (stag is a kind of deer).
'on' means one lot of letters go next to another.
'organised' indicates anagramming the letters.
'freight' anagrammed gives 'efright'.
'stag'+'efright'='STAGE-FRIGHT'
'of' is the link.
(Other definitions for stage fright that I've seen before include "Panic experienced by performer" , "Pre-performance nerves" , "Nervousness in front of audience" , "Performer's fear" , "attack of nerves" .)