Bishop facing additional worry (6)
I believe the answer is:
bother
'worry' is the definition.
(thesaurus)
'bishop facing additional' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'facing' means one lot of letters go next to another.
'additional' becomes 'other' (I've seen this before).
'b'+'other'='BOTHER'
(Other definitions for bother that I've seen before include "Fuss and nuisance" , "Cause annoyance to, pester" , "Annoy, disturb" , "Trouble, fuss" , "Take the trouble to do something" .)