Fine header from Salah after running up for corners (5)
I believe the answer is:
nooks
'corners' is the definition.
('nook' can be a synonym of 'corner')
'fine header from salah after running up' is the wordplay.
'fine' becomes 'ok' (synonyms).
'header from' indicates taking the first letters.
'after' means one lot of letters go next to another.
'running' becomes 'on' (eg when a machine is running it is on).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
The first letter of 'salah' is 's'.
'on' reversed gives 'no'.
'ok'+'s'='oks'
'oks' after 'no' is 'NOOKS'.
'for' is the link.
(Other definitions for nooks that I've seen before include "Cubbyholes" , "Secluded retreats" , "out-of-the-way places" , "secluded parts" , "In security areas" .)