Desire to secure success maybe beyond the pale? (7)
I believe the answer is:
whitish
'maybe beyond the pale?' is the definition.
(pale or somewhat white)
'desire to secure success' is the wordplay.
'desire' becomes 'wish' (wish is a kind of desire).
'to secure' indicates putting letters inside.
'success' becomes 'hit' (hit is a kind of success).
'wish' going around 'hit' is 'WHITISH'.
(Other definitions for whitish that I've seen before include "Pretty snowy" , "Rather pale" , "Nearly snow-coloured" , "cream!" .)