A long time: no point reflecting (3)
I believe the answer is:
eon
'a long time' is the definition.
(I know that eon is a type of long time)
'no point reflecting' is the wordplay.
'point' becomes 'e' (compass point).
'reflecting' is a reversal indicator.
'no'+'e'='noe'
'noe' back-to-front is 'EON'.
(Other definitions for eon that I've seen before include "An immense time" , "Vast age (alt. sp.)" , "Major division of geological time" , "billion years" , "Very long age" .)