Business contractors freely inspect empty rooms around hotel (10)

'business contractors' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.

'freely inspect empty rooms around hotel' is the wordplay.
'freely' indicates an anagram.
'empty' suggests removing the centre.
'around' indicates putting letters inside.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'rooms' with its middle removed is 'rs'.
'inspect'+'rs'='inspectrs'
'inspectrs' with letters rearranged gives 'spincters'.
'spincters' enclosing 'h' is 'SPHINCTERS'.

Can you help me to learn more?