Hostilities in Lancashire initially to secure small upland area (7)
I believe the answer is:
hillock
'small upland area' is the definition.
'hostilities in lancashire initially to secure' is the wordplay.
'initially' says to take the initial letters.
'to secure' becomes 'lock' (locking is a kind of securing**).
The first letters of 'hostilities in lancashire' is 'hil'.
'hil'+'lock'='HILLOCK'
(Other definitions for hillock that I've seen before include "Barrow" , "it requires little effort to get up" , "Mound, knoll" , "elevated ground" , "Rising" .)