Grammar for Everyone - Barbara Dykes 2007

Adverbial clause of manner
Introduction
Part II The parts of speech

This clause tells you more about the way in which something is done.

Finite verbs:  cleaned out, had shown

Main clause:  I cleaned out the tool cupboard

Conjunction:  as

Subordinate clause: she had shown me

Adverbial clause of manner, modifying the verb ’cleaned out’ in the main clause.

Complex sentence