Uncertainty of Sun's leader writers in employ (8)
I believe the answer is:
suspense
'uncertainty' is the definition.
(suspense is a kind of uncertainty)
'sun's leader writers in employ' is the wordplay.
'leader' suggests taking the first letters.
'writers' becomes 'pens' (I've seen this before).
'in' indicates putting letters inside.
'employ' becomes 'use' ('use' can be a synonym of 'employ'**).
The initial letter of 'suns' is 's'.
'pens' placed into 'use' is 'uspense'.
's'+'uspense'='SUSPENSE'
'of' is the link.
(Other definitions for suspense that I've seen before include "Nervous uncertainty; cessation" , "Discontinuance - indecision - excitement" , "Apprehension, anticipation" , "Tense expectation" , "expectancy" .)