Desperate brother -- last to clean and jerk (7)
I believe the answer is:
frantic
'desperate' is the definition.
(I've seen this before)
'brother last to clean and jerk' is the wordplay.
'brother' becomes 'fra' (title for an Italian monk).
'last to' says to take the final letters.
'and' says to put letters next to each other.
'jerk' becomes 'tic' (jerking movement by the body).
The final letter of 'clean' is 'n'.
'fra'+'n'+'tic'='FRANTIC'
(Other definitions for frantic that I've seen before include "Distracted" , "Distraught with fear" , "not collected!" , "'Unrestrained, overly agitated (7)'" , "very worried" .)