Kid is stuck inside railing of staircase (8)
I believe the answer is:
banister
'railing of staircase' is the definition.
'banister' can be an answer for 'railing' (I've seen this before). I am not sure about the 'of staircase' bit.
'kid is stuck' is the wordplay.
I cannot really see how this works, but
'is' is within the answer.
'kid' could be 'banter' (synonyms) and 'banter' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'inside' acts as a link.
Can you help me to learn more?
(Other definitions for banister that I've seen before include "Stair rail" , "Staircase handrail" , "Stair-rail" , "Rail beside a staircase" , "Stair handrail and supports" .)