Extremely unclear man requiring immediate attention (6)
I believe the answer is:
urgent
'requiring immediate attention' is the definition.
(I've seen this before)
'extremely unclear man' is the wordplay.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'man' becomes 'gent' (gent is a kind of man).
'unclear' with its centre taken out is 'ur'.
'ur'+'gent'='URGENT'
(Other definitions for urgent that I've seen before include "Earnest, insistent" , "Pressing, compelling" , "Demanding immediate attention" , "Extremely pressing" , "Pressing, immediate" .)