Page in uniform: my job is emotionally difficult (9)
I believe the answer is:
upsetting
'emotionally difficult' is the definition.
(something upsetting is emotionally difficult)
'page in uniform my job' is the wordplay.
'page' becomes 'p'.
'in' indicates putting letters inside.
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'my job' becomes 'setting' (the crossword setter's job).
'u'+'setting'='usetting'
'p' put inside 'usetting' is 'UPSETTING'.
'is' is the link.
(Other definitions for upsetting that I've seen before include "Tipping" , "sad?" , "Distressing" , "worrying" , "Alarming" .)