Close up, obstruct (7)
I believe the answer is:
occlude
I believe this clue is a double definition.
'close up' is the first definition.
(thesaurus)
'obstruct' is the second definition.
(I know that obstruct can be written as occlude)
(Other definitions for occlude that I've seen before include "Shut out, obscure" , "Block, obstruct" , "Stop up, obstruct" , "Close up (an orifice or passage)" , "Cut or shut off" .)