Amusing actor looks to absorb short lines (5,7)
I believe the answer is:
peter sellers
'amusing actor' is the definition.
(I know this)
'looks to absorb short lines' is the wordplay.
'looks' becomes 'peers' (to peer at something is to look at it).
'to absorb' indicates putting letters inside.
'short' becomes 'terse' (synonyms).
'lines' becomes 'll' (two abbreviations for line).
'terse'+'ll'='tersell'
'peers' enclosing 'tersell' is 'PETER SELLERS'.
(Other definitions for peter sellers that I've seen before include "A Goon; Clouseau actor" , "Inspector Clouseau and leading Goon" , "Old actor" .)