Review of global IT firm in Sky features (5)
I believe the answer is:
nimbi
'sky features' is the definition.
(a nimbus is a cloud)
'review of global it firm in' is the wordplay.
'review of' shows that the letters should be reversed in order.
'global it firm' becomes 'ibm'.
'ibm'+'in'='ibmin'
'ibmin' back-to-front is 'NIMBI'.
(Other definitions for nimbi that I've seen before include "Dark things" , "rings" , "Rain-clouds" , "They may surround the head" , "Rain clouds - halos" .)