Cannot possibly accommodate a child – not I (9)
I believe the answer is:
consonant
'not i' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'cannot possibly accommodate a child' is the wordplay.
'possibly' is an anagram indicator.
'accommodate' is an insertion indicator.
'a child' becomes 'son' (son is a kind of child**).
'cannot' with letters rearranged gives 'conant'.
'conant' placed around 'son' is 'CONSONANT'.
Can you help me to learn more?
(Other definitions for consonant that I've seen before include "Something like G, B and D" , "not I, nor you, one hears" , "B, C, D or F, perhaps?" , "Only one of Ouida's characters is" , "Letter; harmonious chord" .)