Inclined to fear brief prison sentence one day (5)
I believe the answer is:
timid
'inclined to fear' is the definition.
(timid means fearful or scared)
'brief prison sentence one day' is the wordplay.
'brief' means to remove the last letter (a shorter or briefer version of the word).
'prison sentence' becomes 'time' (as in 'doing time').
'one' becomes 'i' (Roman numeral).
'day' becomes 'd' (abbreviation for day).
'time' with its last letter taken off is 'tim'.
'tim'+'i'+'d'='TIMID'
(Other definitions for timid that I've seen before include "Inclined to avoid people" , "Nervous and easily alarmed" , "Lacking self-confidence" , "Easily alarmed, shy" , "Not brave" .)