Unscrupulous type locked in cells, hysterical (7)
I believe the answer is:
shyster
'unscrupulous type' is the definition.
(I know that shysters are unscrupulous people)
'locked in cells hysterical' is the wordplay.
'locked in' says the answer is hidden in the clue.
'SHYSTER' is hidden within 'cells hysterical'.
(Other definitions for shyster that I've seen before include "Pettifogger" , "Wheeler-dealer" , "Unscrupulous practitioner" , "Informally, an unscrupulous or unprofessional person - sounds bashful?" , "Dodgy dealer" .)