Trouble: bishop lived up to expectations (at first) (7)
I believe the answer is:
bedevil
'trouble' is the definition.
(I've seen this before)
'bishop lived up to expectations at first' is the wordplay.
'bishop' becomes 'B' (abbreviation for bishop in chess).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'to' means one lot of letters go next to another (I've seen this in other clues).
'at first' indicates taking the first letters.
The first letter of 'expectations' is 'e'.
'lived' reversed gives 'devil'.
'devil' after 'e' is 'edevil'.
'b'+'edevil'='BEDEVIL'
(Other definitions for bedevil that I've seen before include "Cause difficulties for, like Satan?" , "trouble" , "Torture" , "Worry, harass" , "Cause continual difficulties" .)