Plan for sheep to wander outside (8)
I believe the answer is:
strategy
'plan' is the definition.
(strategy is a kind of plan)
'sheep to wander outside' is the wordplay.
'sheep' becomes 'teg' (I've seen this before).
'to wander' becomes 'stray' ('stray' can be a synonym of 'wander').
'outside' is an insertion indicator.
'teg' placed within 'stray' is 'STRATEGY'.
'for' acts as a link.
(Other definitions for strategy that I've seen before include "Grand design" , "Planning and direction of campaign" , "Plan of action, tactics" , "Plan or policy as for conducting campaign" , "Systematic plan of action" .)