Segregating giant soil formation (9)
I believe the answer is:
isolating
'segregating' is the definition.
Although both the answer and definition are present participle verbs, I don't see how one could define the other.
'giant soil formation' is the wordplay.
'formation' indicates anagramming the letters.
'giant'+'soil'='giantsoil'
'giantsoil' is an anagram of 'ISOLATING'.
Can you help me to learn more?
(Other definitions for isolating that I've seen before include "Ligations (anag.)" , "Detaching, separating" , "maintaining detachment?" .)