Work out approach to secure place (7)
I believe the answer is:
compute
'work out' is the definition.
(I know that work out can be written as compute)
'approach to secure place' is the wordplay.
'approach' becomes 'come' (e.g. as imperative).
'to secure' indicates putting letters inside (inserted letters are secured inside).
'place' becomes 'put' (synonyms).
'come' going around 'put' is 'COMPUTE'.
(Other definitions for compute that I've seen before include "Work out" , "Calculate, maybe electronically" , "Reckon, calculate" .)