Blockade, for example, is about to surround Spain (5)
I believe the answer is:
siege
'blockade' is the definition.
(siege is a kind of blockade)
'example is about to surround spain' is the wordplay.
'example' becomes 'eg'.
'about' says the letters should be written in reverse.
'to surround' is an insertion indicator.
'spain' becomes 'e' (abbreviation for Espana).
'eg'+'is'='egis'
'egis' back-to-front is 'sige'.
'sige' placed around 'e' is 'SIEGE'.
'for' is the link.
(Other definitions for siege that I've seen before include "Military operation to seal off (town)" , "seat" , "Military encirclement" , "Blockade of a town or fortress" , "Operation to capture a fort, for example" .)