Reviewer little man very sick (8)
I believe the answer is:
critical
'very sick' is the definition.
(in critical condition)
'reviewer little man' is the wordplay.
'reviewer' becomes 'critic' (I've seen this before).
'little man' becomes 'Al' (short for Alex, Alastair etc).
'critic'+'al'='CRITICAL'
(Other definitions for critical that I've seen before include "Censorious - to a dangerous degree" , "Decisive - grave" , "Condemnatory; vital" , "like one in an armchair perhaps" , "Key" .)