Occasionally meet star climbing this? (4)
I believe the answer is:
mesa
'climbing this?' is the definition.
(mesa is a type of hill)
'occasionally meet star' is the wordplay.
'occasionally' indicates alternate letters.
'meet'+'star'='meetstar'
The alternate letters of 'meetstar' are 'MESA'.
(Other definitions for mesa that I've seen before include "Flat-topped mountain" , "US steep-sided tableland" , "Flat tableland with steep sides" , "In the US south-west, a steep-sided flat-topped hill" , "Flat-topped tableland" .)