Uniform with plaid top's ill-fitting and prickly (7)
I believe the answer is:
uptight
'prickly' is the definition.
(both can mean irritable or cranky)
'uniform with plaid top's ill-fitting' is the wordplay.
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'with' means one lot of letters go next to another.
'top's' says to take the initial letters (I've seen 'topped' mean this).
'ill-fitting' becomes 'tight' (as in poorly fitting clothing).
The first letter of 'plaid' is 'p'.
'u'+'p'+'tight'='UPTIGHT'
'and' acts as a link.
(Other definitions for uptight that I've seen before include "Nervous, tense, anxious" , "Informally, nervously tense and anxious" , "Nervously tense (colloq.)" , "Highly-strung" , "Tense - cross" .)