Sentence:  Private-equity nabobs bristle at being dubbed mere financiers. Piling debt onto companies' balance-sheets is <WSD>only</WSD> a small part of what leveraged buy-outs are about, they insist. Improving the workings of the businesses they take over is just as core to their calling, if not more so. Much of their pleading is public-relations bluster. 
Meaning of the word marked with <WSD> tags:  No more than; just.