Reaching a junction in giant formation (9)
I believe the answer is:
attaining
'reaching' is the definition.
('attain' can be a synonym of 'reach')
'a junction in giant formation' is the wordplay.
'junction' becomes 't'.
'formation' is an anagram indicator.
'in'+'giant'='ingiant'
'ingiant' with letters rearranged gives 'taining'.
'a'+'t'+'taining'='ATTAINING'
(Other definitions for attaining that I've seen before include "Reaching" , "Accomplishing, achieving" .)